iio: imu: inv_mpu6050: better fifo overflow handling

Use fifo overflow bit from int status rather than using an
arbitrary threshold.
Signed-off-by: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h

@@ -166,6 +166,7 @@ struct inv_mpu6050_state {
 #define INV_MPU6050_REG_RAW_GYRO            0x43
 
 #define INV_MPU6050_REG_INT_STATUS          0x3A
+#define INV_MPU6050_BIT_FIFO_OVERFLOW_INT   0x10
 #define INV_MPU6050_BIT_RAW_DATA_RDY_INT    0x01
 
 #define INV_MPU6050_REG_USER_CTRL           0x6A
@@ -190,7 +191,6 @@ struct inv_mpu6050_state {
 
 #define INV_MPU6050_BYTES_PER_3AXIS_SENSOR   6
 #define INV_MPU6050_FIFO_COUNT_BYTE          2
-#define INV_MPU6050_FIFO_THRESHOLD           500
 
 /* mpu6500 registers */
 #define INV_MPU6500_REG_ACCEL_CONFIG_2      0x1D

drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c

@@ -110,6 +110,9 @@ irqreturn_t inv_mpu6050_read_fifo(int irq, void *p)
 			"failed to ack interrupt\n");
 		goto flush_fifo;
 	}
+	/* handle fifo overflow by reseting fifo */
+	if (int_status & INV_MPU6050_BIT_FIFO_OVERFLOW_INT)
+		goto flush_fifo;
 	if (!(int_status & INV_MPU6050_BIT_RAW_DATA_RDY_INT)) {
 		dev_warn(regmap_get_device(st->map),
 			"spurious interrupt with status 0x%x\n", int_status);
@@ -135,8 +138,6 @@ irqreturn_t inv_mpu6050_read_fifo(int irq, void *p)
 	if (result)
 		goto end_session;
 	fifo_count = get_unaligned_be16(&data[0]);
-	if (fifo_count >  INV_MPU6050_FIFO_THRESHOLD)
-		goto flush_fifo;
 	/* compute and process all complete datum */
 	nb = fifo_count / bytes_per_datum;
 	for (i = 0; i < nb; ++i) {